Corn Yield Response to Timing of Strip-Tillage and Nitrogen Source Applications

Development of effective management practices to maximize corn (Zea mays L.) production is important in poorly drained claypan soils due to their relatively low yield potential and vulnerability for environmental N loss. The objective of this 3-yr study, conducted at one location was to determine whether an N management system with strip-till (ST) and deep banding placement of polymer-coated urea (PCU) could produce greater corn yields than no-till (NT) systems with broadcasted non-coated urea (NCU) or injected anhydrous ammonia (AA) with or without nitrapyrin with fall, early pre-plant, or pre-plant N applications. The experiment was a split-plot design with N application dates as the main plot and eight N management systems (N source and tillage/N placement) as subplots. Nitrogen sources of PCU, NCU, and a non-treated control (NTC) were used in conjunction with NT/surface broadcast and ST/deep band placement practices. Anhydrous ammonia was injected into a NT soil with or without nitrapyrin. Injecting AA into a NT soil with nitrapyrin at pre-plant produced at least 2 Mg ha(-1) greater corn yields than any of the management systems with a fall application during three wet years. When N was applied in the fall or at early pre-plant, ST/deep banding of PCU and NCU produced yields similar to NT/injected AA with or without nitrapyrin. Strip-tillage with deep banding of urea fertilizers may be a viable, high yielding alternative N management system in poorly drained claypan soils when tillage and N applications are done in fall.